An as large as possible mirror diameter, e.g. larger than 7 millimeters, an as high as possible resonant frequency, i.e. high scanning frequencies, e.g. greater than 7 kilohertz, and an as large as possible deflection angle, e.g. larger than 10°, are simultaneously desired for numerous applications of micromirror arrangements.
A micromirror arrangement, with which a single-axis spring-mass oscillator is suspended in a further spring-mass oscillator is known from U.S. Pat. No. 5,543,956. Thereby, a drive unit which excites the further spring-mass oscillator into oscillation is assigned to the further spring-mass oscillator, by which means the suspended single-axis spring-mass oscillator is likewise excited into oscillation. The single-axis spring-mass oscillator comprises an oscillation body which is designed as a mirror and which is suspended on a drive plate of the further spring-mass oscillator via torsion springs, and this drive plate in turn is connected to a stationary part via torsion springs. A resonant oscillation of the single-axis spring-mass oscillator which is designed as an inner mirror oscillator and whose amplitude has a large deflection angle and is significantly increased with respect to the surrounding drive plate, can be realised given a suitable design of the moments of inertia and spring stiffnesses of the spring-mass oscillators as well as with a suitable selection of the activation frequency for the drive of the further spring-mass oscillator.
Such micromirror arrangements which are known from the state of the art and which are applied as so-called MEMS scanners are all limited to only single-axis systems. However, a resonant oscillation in two axes perpendicular to one another, e.g. for Lissajous laser projection displays, is desirable for numerous tasks.
Biaxial resonance scanners with a biaxial amplitude amplification are to be found in literature only to a limited extent. Schenk et al. in the article “Design and Modeling of Large Deflection Micromechanical 1D and 2D Scanning Mirrors”, Proceedings of SPIE, vol. 4178 (2000) describes a cardanically suspended biaxially resonant 2D scanner which has a mirror diameter of less than 2 millimeters. This approach, based on electrostatic comb drives would lead to an extremely disadvantageously enlarged component for large mirrors, for example for mirrors with 7 millimeters and larger, and this component would then only have very low dynamics due to the scaling of the electrostatic forces.
A different approach is described in U.S. Pat. No. 7,295,726 B1. The biaxial scanner which is known from this makes do without a cardanic suspension and utilises four identical lever connections between the scanner chip flame and a mirror plate. The electrode distances can be kept small with this biaxial scanner, but an unfavourable scaling behaviour of the electrostatic force also occurs with this approach.